A full understanding of the mechanics of uRPF (the different behaviors of the two modes especially), along with knowing the basic configuration and theory of how VACLs work, so when you are faced with tricky word play / config examples of either on a Cisco exam or while on the job troubleshooting a production network! … Continue reading TSHOOT – Unicast Reverse Path Forwarding (uRPF), and VLAN Access-List (VACL) details reviewed for exam day!
These 3 diagrams have been publicly available for years, I downloaded this TSHOOT Topology off Cisco's official learning forum, post can be viewed here. I doubt this is exactly the Topology used on exam day, it very well could be, however if this is not it the Topology will be something extremely similar to this. … Continue reading TSHOOT – Critical understanding of Cisco Published Topologies, troubleshooting methods, and must knows for exam day!
Above is the IP Packet Switching architecture, with the IP Route / ARP Table at the "Control Plane" at the Top, which then feeds the FIB (Forward Information Base) aka IP CEF and Adjacency Table to perform Hardware Packet Switching. Packet Switching is covered extremely in depth in this article, however it will be briefly … Continue reading TSHOOT – IPv4 Route Selection / Packet Switching process, Static Routing for IPv4 and IPv6 with troubleshooting!
Above is a quick reminder of different Hex values, given the previous post on FHRP troubleshooting which includes the VLAN / Router Group in Hex format. Click here for my full Hex Conversion article. It will be needed for IPv6 troubleshooting! Now a quick but necessary review of IPv4 identification! It is important to be … Continue reading TSHOOT – Hex, IPv4 Addressing, DHCP, and IP NAT review and troubleshooting!
Will cover the three FHRP's for the CCNP R/S in the article, review some very basics of each protocol, and jump into commands to troubleshoot them on TSHOOT day! HSRP (Hot Standby Router Protocol) Review and Troubleshooting Review HSRP is Cisco Propriety HSRP works on both Layer 3 switches and Cisco Routers Hello 3 sec … Continue reading TSHOOT – HSRP, VRRP, and GLBP First Hop Redundancy Protocol review and troubleshooting!
Above is a visual of Private VLANs and how they can communicate with each other, however this is going to be a lot of Switch security, so lets get to it. Port Security troubleshooting Some common issues that can cause Port Security not to work: Port Security is configured but not enabled - This is … Continue reading TSHOOT – Port Security, DHCP Snooping, IP Source Guard, DAI, Protected Ports, Private VLANs, and VACL Troubleshooting!
Above is a simple STP topology from earlier SWITCH labbing, however this will cover all STP flavors (PVST+ / RSTP / MSTP), features that go with them, and EtherChannels. STP issues, how to identify and resolve them, and feature behaviors In relation to the TSHOOT exam, the most important thing to note is that the … Continue reading TSHOOT – Troubleshooting Spanning-Tree and Layer 2 EtherChannel issues!
The troubleshooting of Layer 2 issues seems like it may be the easiest, as the information is really taught quite thorough at the CCNA level, however there are some caveats that are potential exam landmines for TSHOOT to avoid on exam day! First I want to start with some verification commands that are critical for … Continue reading TSHOOT – Layer 2 troubleshooting of Trunks, VTP, and VLANs!